Fire Detection and Suppression Chapter 2 Fire Detection and Signaling Systems

Fire Detection and Signaling Systems The early detection of a fire and the signaling of an appropriate alarm remain the most significant factors in preventing large losses from occurring. Fire Detection and Signaling Systems

Fire Detection and Signaling Systems Standards and Codes Component tests by nationally recognized labs Underwriters Laboratories Factory Mutual Codes NFPA 70, National Electrical Code NPFA 72, The National Fire Alarm Code Local codes and ordinances Fire Detection and Signaling Systems

Basic System Components System control unit (alarm panel) Brain of system Processes alarm signals from actuating devices and transmits them to the local or other alerting system Fire Detection and Signaling Systems

Basic System Components (cont.) Power supply Primary power supply Public electric utility Engine-driven generator Secondary power supply Storage battery and charger Engine-driven generator and 4-hour storage battery Multiple engine-driven generators Trouble signal power supply Fire Detection and Signaling Systems

Basic System Components (cont.) Initiating devices: manual pull stations, heat detectors, smoke detectors, flame detectors, waterflow devices, tamper switches, and combination detectors Notification appliances: bells, buzzers, horns, recorded voice messages, strobe lights, speakers, and other warning appliances Auxiliary services Fire Detection and Signaling Systems

Types of Fire Alarm Systems Selection factors Level of life-safety hazard Structural features of the building Level of hazard presented by the contents of the building Availability of fire suppression resources State and local code requirements (Continued) Fire Detection and Signaling Systems

Types of Fire Alarm Systems (cont.) Local system Noncoded local alarm Simultaneous operation of all alarm-indicating devices Only practical in small occupancies with limited number of rooms Master coded local alarm Serves the premises as a local control unit and receives input from other fire alarm control units Used in occupancies that use the alarm signals for other purposes (Continued) Fire Detection and Signaling Systems

Types of Fire Alarm Systems Local system (cont.) Zoned/annunciated alarm Identifies fire location quickly and accurately Alarm-initiating devices arranged in circuits or zones Initiating device sounds alarm and lights corresponding lamp on control unit Annunciator panel remote from control panel Coded signals Presignal alarm (Continued) Fire Detection and Signaling Systems

Types of Fire Alarm Systems (cont.) Auxiliary system Facility that receives signals where personnel are always present to respond Initiation devices Local requirements and policies Types of auxiliary systems Local energy system Shunt system Parallel telephone system (Continued) Fire Detection and Signaling Systems

Types of Fire Alarm Systems (cont.) Remote station system Connected to dispatch center by means other than municipal fire alarm box system Local alarm capability Monitoring options (Continued) Fire Detection and Signaling Systems

Types of Fire Alarm Systems (cont.) Proprietary system Used to protect large buildings or facilities Systems for individual buildings or areas wired into common receiving point Wide-ranging capabilities (Continued) Fire Detection and Signaling Systems

Types of Fire Alarm Systems (cont.) Central station system Similar to proprietary system but receiving point is an outside, contracted central station Alarm activation information received by central station employees, who initiate emergency response (Continued) Fire Detection and Signaling Systems

Types of Fire Alarm Systems (cont.) Emergency voice/alarm communications system Supplements other systems Communicates detailed information to occupants and fire fighting personnel One-way/two-way Fire Detection and Signaling Systems

Manual Alarm-Initiating Devices General requirements Mounting and distribution Generally not required in fully sprinklered structures Outmoded “broken glass” pull stations Coded versus noncoded pull stations Single-action and double-action pull stations Fire Detection and Signaling Systems

Automatic Alarm-Initiating Devices Continuously monitor atmosphere Four basic types Heat detectors Smoke detectors Fire-gas detectors Flame detectors Fire Detection and Signaling Systems

Fire Detection and Signaling Systems Heat Detectors Fixed temperature heat detectors Fusible links/frangible bulbs Continuous line detector Bimetallic detector Rate-of-rise heat detector Pneumatic rate-of-rise spot detector (Fig. 2.34) Pneumatic rate-of-rise line detector (Fig. 2.35) Rate compensated detector (Fig. 2.36) Thermoelectric detector Fire Detection and Signaling Systems

Fire Detection and Signaling Systems Smoke Detectors Photoelectric smoke detector Projected beam (Fig. 2.37) Refractory photocell (Fig. 2.38) Ionization smoke detector (Fig. 2.39) Dual chamber Air-sampling smoke detectors Cloud chamber (Fig. 2.40) Second type (Fig. 2.41) (Continued) Fire Detection and Signaling Systems

Smoke Detectors (cont.) Limitations May not provide early warning of a fire developing on another level of a building May not detect fire developing on the other side of a closed door May not be effective when fire is caused by explosions resulting from careless housekeeping Fire Detection and Signaling Systems

Fire Detection and Signaling Systems Flame Detectors Types Ultraviolet (UV) Fig. (2.42a) Infrared (IR) Fig. (2.42b) Fast to respond Frequent false alarms Fire Detection and Signaling Systems

Fire Detection and Signaling Systems Fire Gas Detectors Monitors levels of gases released by combustion Carbon dioxide Carbon monoxide Faster than heat detectors but slower than smoke detectors Fire Detection and Signaling Systems

Combination Detectors Various possible combinations Fixed rate/rate-of-rise detectors Heat/smoke detectors Smoke/fire gas detectors Offer benefits of both systems and increase responsiveness to fire conditions Fire Detection and Signaling Systems

Fire Detection and Signaling Systems Acceptance Testing Should be observe by representatives of building owner, fire department, system installer, and system manufacturer. All functions of the fire detection and signaling system should be operated: All alarm-indicating and alarm-initiating devices Restorable heat detectors Response of outside entities responsible for monitoring the system Fire Detection and Signaling Systems

Fire Detection and Signaling Systems General Inspections Fire department participation Checkpoints Condition of wiring and batteries All equipment free of foreign materials Adequate clearance around system control units, recording instruments, and other devices Fire Detection and Signaling Systems

Inspecting and Service Testing Initiating Devices (cont.) Manual alarm-initiating devices Automatic alarm-initiating devices Detectors must not be damaged or painted. Replace or send the following detectors to a recognized testing laboratory for testing: Detectors on systems that are being restored to service after a period of disuse Detectors that are obviously corroded (Continued) Fire Detection and Signaling Systems

Inspecting and Service Testing Initiating Devices (cont.) Automatic alarm-initiating devices Replace or send the following detectors to a recognized testing laboratory for testing (cont.): Detectors that have been painted over, even if attempts were made to clean them Detectors that have been mechanically damaged or abused Detectors on circuits that were subjected to current surges, overvoltages, or lightning strikes (Continued) Fire Detection and Signaling Systems

Inspecting and Service Testing Initiating Devices (cont.) Automatic alarm-initiating devices Replace or send the following detectors to a recognized testing laboratory for testing (cont.): Detectors subjected to foreign substances that might affect their operation Detectors subjected to either direct flame, excessive heat, or smoke damage Testing Nonrestorable Restorable Fire Detection and Signaling Systems

Inspecting System Control Units Control panel switches and functions Auxiliary devices Receiving signals Fire Detection and Signaling Systems

System Testing Timetables Local systems: local guidelines Central station systems: monthly Auxiliary systems: monthly (noncoded fire alarm boxes: monthly) Remote station and proprietary systems: authority having jurisdiction Emergency voice/alarm systems: quarterly NOTE: In all cases, check the most current edition of NFPA 72, National Fire Alarm Code. Fire Detection and Signaling Systems

Fire Detection and Signaling Systems Record Keeping Maintaining Files and Records Documents: Inspection reports, forms, and letters Violation notices Summonses Plans review comments, approvals, and drawings Fire reports Investigations Permits and certificates issued (Continued) Fire Detection and Signaling Systems

Fire Detection and Signaling Systems Record Keeping Maintaining Files and Records (cont.) Occupancies: Those that have been issued a permit, certificate, or license Those that contain automatic fire suppression or detection systems Those that conduct hazardous operations or routinely house hazardous materials Duration: life of structure Public record (Continued) Fire Detection and Signaling Systems

Fire Detection and Signaling Systems Record Keeping (cont.) Written records File for each inspected property Cataloging and storage Electronic records Two primary methods of entering data: Inspectors use laptop computers or handheld electronic data recording equipment during the inspection. Inspectors use written forms during the inspection and then enter the information upon returning to the office. (Continued) Fire Detection and Signaling Systems

Fire Detection and Signaling Systems Record Keeping (cont.) Electronic records (cont.) Considerations in computer system management How will the information be filed? How can the information be retrieved? What portion of the information will be stored in a read-only format? What personnel will be given access to retrieve information from the system? What information can be released to the public? Fire Detection and Signaling Systems